Spectroscopic Study of Dye Isomerization in a Host-Guest Complex
Arts and Sciences
Host-guest complexes are systems in which a guest molecule binds to a host molecule through weak intermolecular interactions. β-cyclodextrin, the host molecule, is a seven-membered ring with a hydrophobic inner cavity and a hydrophilic outer surface. Brooker’s merocyanine, the guest, is a dye molecule with a photo-induced isomerization cycle. The isomerization of Brooker’s merocyanine was analyzed using UV-Vis spectroscopy to understand differences in the behavior of the dye in the solution and within modified β-cyclodextrin cavities. The molecule in solution undergoes minimal isomerization from the trans to cis configuration unless UV light is added. However, when the deprotonated dye is complexed with β-CD, it undergoes extensive isomerization without UV light exposure to relieve the strain inflicted by the cavity. Different chemical modifications, such as methyl β-CD, hydroxypropyl-β-CD and hydroxyethyl-β-CD, to the outer surface of the cyclodextrin have been studied to see how these modifications might affect this unique isomerization behavior. Further studies are being conducted to examine the binding of the different isomers of Brooker’s merocyanine to the modified β-cyclodextrins. By understanding guest behavior in the cavity, a molecular level understanding of host-guest chemistry will help to improve the practical applications of these materials.
Repak, Miroslava, "Spectroscopic Study of Dye Isomerization in a Host-Guest Complex" (2015). Symposium on Undergraduate Research and Creative Expression (SOURCE). 470.